請實現一個函數按照之字形打印二叉樹,即第一行按照從左到右的順序打印,第二行按照從右到左的順序打印,第三行按照從左到右的順序打印,其他行一次類推。
class TreeNode:
def __init__(self,x):
self.val = x
self.left = None
self.right = None
class Solution:
def Print(self, pRoot):
if pRoot==None:
return []
stack1=[pRoot]
stack2=[]
ret = []
while stack1 or stack2:
if stack1:
tmpRet=[]
while stack1:
tmpNode=stack1.pop()
tmpRet.append(tmpNode.val)
if tmpNode.left:
stack2.append(tmpNode.left)
if tmpNode.right:
stack2.append(tmpNode.right)
ret.append(tmpRet)
if stack2:
tmpRet=[]
while stack2:
tmpNode = stack2.pop()
tmpRet.append(tmpNode)
if tmpNode.right:
stack1.append(tmpNode.right)
if tmpNode.left:
stack1.append(tmpNode.left)
ret.append(tmpRet.val)
return ret